The Biggs Site (15Gp8), also known as the Portsmouth Earthworks Group C, is an Adena culture archaeological site located near South Shore in Greenup County, Kentucky. Group C was originally a large series of concentric circular embankments and ditches surrounding a central conical burial mound. It was part of a larger complex, the Portsmouth Earthworks located across the Ohio River, now mostly obliterated by agriculture and the developing city of Portsmouth, Ohio. The site was surveyed and mapped by E. G. Squier in 1847 for inclusion in the seminal archaeological and anthrolopological work Ancient Monuments of the Mississippi Valley.